feat: Integration with Cumulocity CA

[didier-wenzek]

Proposed changes

• Impl tedge cert download c8y
• Impl tedge cert renew c8y
• Enhance tedge config with setting for certificate validity period.
• Enhance tedge cert show to display number of days before expiration.
• Make sure the current certificate is not erased on renewal

Types of changes

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Improvement (general improvements like code refactoring that doesn't explicitly fix a bug or add any new functionality)
• Documentation Update (if none of the other choices apply)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Paste Link to the issue

#3248

Checklist

• I have read the CONTRIBUTING doc
• I have signed the CLA (in all commits with git commit -s)
• I ran cargo fmt as mentioned in CODING_GUIDELINES
• I used cargo clippy as mentioned in CODING_GUIDELINES
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)

Further comments

[codecov]

Codecov Report

Attention: Patch coverage is 4.06504% with 236 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
...tes/core/tedge/src/cli/certificate/c8y/download.rs	0.00%	81 Missing ⚠️
crates/core/tedge/src/cli/certificate/c8y/renew.rs	0.00%	52 Missing ⚠️
crates/core/tedge/src/cli/certificate/cli.rs	0.00%	42 Missing ⚠️
crates/core/tedge/src/cli/certificate/c8y/mod.rs	0.00%	29 Missing ⚠️
.../tedge_config/src/tedge_config_cli/tedge_config.rs	32.00%	10 Missing and 7 partials ⚠️
crates/core/tedge/src/cli/certificate/mod.rs	0.00%	9 Missing ⚠️
crates/core/tedge/src/cli/certificate/create.rs	28.57%	3 Missing and 2 partials ⚠️
crates/core/c8y_api/src/json_c8y_deserializer.rs	0.00%	1 Missing ⚠️

Additional details and impacted files

📢 Thoughts on this report? Let us know!

[didier-wenzek]

One needs to loop only when it makes senses to retry: i.e. the c8y endpoint has been reached but the device has not been registered yet.

Question: does Cumulocity return a specific HTTP status when the device is not registered?

[github-actions]

Robot Results

✅ Passed	❌ Failed	⏭️ Skipped	Total	Pass %	⏱️ Duration
570	0	3	570	100	1h33m53.885902999s

[didier-wenzek]

Something is wrong here.

In tedge cert renew c8y, c8y can be understood either as the CA and as the cloud profile. Even clap is confused:

• tedge cert renew self-signed c8y --profile test is correctly interpreted as a request to renew the self-signed certificate used to connect the test c8y tenant
• while tedge cert renew c8y c8y --profile test leads to an error, clap incorrectly assuming the default CA (i.e. self-signed) and being then confused by the repeated cloud parameter.